What is the MIME type of .yaml files?
The MIME type (media type) for YAML files with the .yaml extension is application/yaml. You may also see text/yaml, application/x-yaml. Registered as application/yaml in RFC 9512 (2024). Older systems use text/yaml or application/x-yaml.
Content-Type header
Content-Type: application/yaml; charset=utf-8Text-based types should include a charset so the browser decodes characters correctly.
Server configuration
| Server | Configuration |
|---|---|
Nginx (mime.types or types {}) | application/yaml yaml; |
Apache (.htaccess) | AddType application/yaml .yaml |
IIS (web.config) | <mimeMap fileExtension=".yaml" mimeType="application/yaml" /> |
| Node.js / Express | res.type('yaml') or res.setHeader('Content-Type', 'application/yaml; charset=utf-8') |
| Amazon S3 | Set Content-Type: application/yaml on the object (metadata), or pass --content-type application/yaml to aws s3 cp |
Should .yaml files be compressed?
Yes. YAML is text, so enabling gzip or Brotli for application/yaml typically saves 50–80 % of the transfer size. Make sure your server’s compression list includes this type — check with the website compression test.
Why the MIME type matters
Browsers decide what to do with a response — render, run, play or download — from the Content-Type header, not the file extension. With X-Content-Type-Options: nosniff, a wrong type causes stylesheets and scripts to be blocked outright. For uploads, never trust the type sent by the client; check the file’s content (its magic bytes) on the server.
Frequently asked questions
What is the MIME type for .yaml?
application/yaml. Alternatives seen in the wild: text/yaml, application/x-yaml.How do I set the Content-Type for .yaml in Nginx?
application/yaml yaml; is listed in the types block (usually in /etc/nginx/mime.types) and reload Nginx.